Black Hat USA 2012 - Confessions of a WAF Developer: Protocol-Level Evasion of Web App Firewalls

From a channel Lumen includes in full: Black Hat's briefings are peer-selected security research talks — exploitation, cryptography, hardware and cloud attacks — presented by the researchers who did the work, usually with full technical detail and disclosure timelines.

A 47-minute video from Black Hat's catalogue; the title names its topic.

Video by Black Hat, played through YouTube's embedded player.